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Dataset: Nationwide Readmission Database (NRD)

Basic Information
Dataset Full Name Nationwide Readmission Database
Dataset Acronym NRD
Summary The NRD is a recently developed (2013) annual database by the Agency for Healthcare Research and Quality (AHRQ) and contains over 14 million records and more than 100 clinical and non-clinical data elements. The database is designed for tracking all types of national readmission rates across all types of payers as well as uninsured individuals. “All payers” include patients enrolled through Medicare, Medicaid, and private insurance. It was developed by the Healthcare Cost and Utilization Project (HCUP) with the help of Federal, State, and Industry collaboration and supported by the Agency for Healthcare Research and Quality (AHRQ). The NRD is drawn from the HCUP State Inpatient Database (SID), and includes information on patient discharges with and without repeat hospital visits in a year and those who have died in the hospital. Repeated stays may or may not be related. The NRD addresses a current gap in health service research by providing nationally representative weighted data across all age groups, payers, and the uninsured population.
Key Terms HCUP, HCUP State Inpatient Database , AHRQ, National, Readmission, Hospital Discharge, Medicare, Medicaid, Uninsured
Study Design Longitudinal
Data Type(s) Administrative
Sponsoring Agency/Entity Department of Health and Human Services (HHS): Agency for Health care Research and Quality (AHRQ)
Health Conditions/Disability Measures
Health Condition(s)

ICD-9 diagnostic codes

Disability Measures N/A
Measures/Outcomes of Interest
Topics Patient demographics: sex, age, median household income quartile, and urban/rural location of the patient's residence, etc. Source of payment: Medicare, Medicaid, private insurance, uninsured, and other insurance types. Hospital cost (calculated using the Cost-to-Charge Ratio file), patient readmission rates, readmission reason, hospital discharge costs: with and without readmissions. Clinical and nonclinical variables relevant to readmission: external cause of injury codes, procedure codes, diagnosis and procedure classifications variables using Clinical Classification Software (CCS) category and Chronic Condition Indicator (CCI).
Sample Population Hospital inpatient stays for all types of payers and the uninsured drawn from HCUP State Inpatient Databases (SID) of the 21 HCUP partner states (accounting for 49.1 percent of all U.S. hospitalizations). Includes stays at community hospitals- defined as short-term, non-Federal, general, and other hospitals such as obstetrics and gynecology, otolaryngology, orthopedic, cancer, pediatric, public, and academic medical hospitals. Data excludes: Federal hospitals (Department of Defense, Veterans Administration, Indian Health Services, and Department of Justice [prison] hospitals) hospital units of other institutions, long-term care facilities such as rehabilitation, long-term acute care, psychiatric, and alcoholism and chemical dependency hospitals.
Sample Size/Notes Approximately 14 million discharges each year (~ 36 million discharges when weighted to create national estimates). Stratum is used for weighting to generate national estimates. Discharge weights for national estimates were developed using the target universe of community hospitals (excluding rehabilitation and long-term acute care hospitals) in the United States
Unit of Observation Patient hospital discharge
Continent(s) North America

United States

Geographic Coverage 2013 NRD data includes discharge data from 21 geographically dispersed states accounting for nearly half of the total U.S. population: Arkansas, California, Florida, Georgia, Hawaii, Iowa, Louisiana, Massachusetts, Missouri, Nebraska, New Mexico, Nevada, New York, South Carolina, South Dakota, Tennessee, Utah, Virginia, Vermont, Washington, and Wisconsin. The states included in the NRD may change over time.
Geographic Specificity National
Data Collection
Data Collection Mode The 2013 NRD was constructed from the HCUP State Inpatient Database (SID). This database includes records from 21 States utilizing reliable, verified patient linkage numbers that allows the tracking of patients across hospitals within a state. Patient linkage numbers identify discharges belonging to the same individual.
Years Collected 2013 - ongoing
Data Collection Frequency Annual
Strengths and Limitations
Strengths Large sample size, weighted, nationally representative, captures all types of payers and the uninsured, includes readmissions for relatively uncommon disorders, permits examination of the relationship between multiple hospital admissions for an individual patient in a calendar year, allows estimation of hospital costs for patients with and without readmission. The verified patient linkage numbers allow the tracking of patients across hospitals within a state and identifies discharges belonging to the same individual. Time of admissions and discharge are used to calculate the length of stay, transfers, same-day stays, and combined transfer records.
Limitations The NRD does not include data from non-community hospitals, inpatient rehabilitation or Skilled Nursing Facilities. No data element is provided to identify if sequential inpatient stays are related or not - determination of relationships between patient stays is left up to the researcher. NRD only includes discharges occurring within the calendar year, it excludes patients admitted in current year but discharged in the following year. Patients can only be linked within a state, readmissions and discharges in another state cannot be associated. Cannot be used for generating state, regional, or hospital-specific estimates. Has significant hardware requirements due to large file size (SAS file 12GB, SPSS 23 GB).
Data Details
Primary Website


Data Access


Data Access Requirements Data Use agreement, $ Cost
Summary Tables/Reports

NRD Summary Statistics:


Data Components

The NRD is comprised of three discharge-level files and one hospital-level file:

  • Discharge-level files include : Core File: Variables critical to readmission analyses
  • Severity file : Variables that can be used to identify the severity of the condition for a specific discharge
  • Diagnosis and Procedure Groups File: Contains additional information on the diagnoses (e.g., chronic condition indicators) and procedures (e.g. procedure class)
  • Hospital-level File: Hospital characteristics
Similar/Related Dataset(s)

Health care Cost & Utilization Project (HCUP): State Inpatient Database (SID)

Health care Cost & Utilization Project (HCUP): Kids' Inpatient Database (KID)

Health care Cost & Utilization Project (HCUP): Nationwide Inpatient Sample (NIS) 

Selected Papers
Other Papers

Barrett M., Steiner C., Andrews R., Kassed C., Nagamine M. Methodological Issues when Studying Readmissions and Revisits Using Hospital Administrative Data. 2011. HCUP Methods Series Report # 2011-01.


Barrett M., Raetzman S., Andrews R. Overview of Key Readmission Measures and Methods. 2012. HCUP Methods Series Report #2012 -04.


HCUP Statistical Briefs - Readmissions and Revisits


HCUP Statistical Briefs - Preventable Hospitalizations:



NRD Database Documentation:


Introduction to the HCUP Nationwide Readmissions Database (NRD) 2013


NRD Availability of Data Elements by Year:


NRD Description of Data Elements:


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The Rehabilitation Research Cross-dataset Variable Catalog has been developed through the Center for Large Data Research & Data Sharing in Rehabilitation (CLDR). The Center for Large Data Research and Data Sharing in Rehabilitation involves a consortium of investigators from the University of Texas Medical Branch, Cornell University's Yang Tan Institute (YTI), and the University of Michigan. The CLDR is funded by NIH - National Institute of Child Health and Human Development, through the National Center for Medical Rehabilitation Research, the National Institute for Neurological Disorders and Stroke, and the National Institute of Biomedical Imaging and Bioengineering. (P2CHD065702).

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